A group communications system allows a plurality of users to participate in a group communication session with each other through a plurality of corresponding user communication devices interconnected through a communications network. Such a system may also include a controller device to facilitate coordination of communications in the group and access to communication resources associated with the group, i.e., the control device may assist with “floor control”. One purpose of floor control is to ensure that only one user communication device is transmitting data at any one time, while other user communication devices associated with the group communication session only receive data during the same time. Floor control also provides the method with which the right to transmit data and access to communication resources associated with the group are shared between the plurality of user devices. This typically involves user communication devices sending “floor request” signals to the controller device and the controller device “granting the floor” to user devices according to some policy, e.g., first come first served.
While floor control functions can apply to any form of data communications, they are particularly useful in voice communications, since during a conversation amongst a group of people it is beneficial if there is only one speaker at any one time. Note that digitized and packetized voice is simply a subset of data communications.
The one sender many receivers property of a group communications session is exploited so that communication resources for sending data are only required by a single user communication device at a time, while communication resources for receiving data are required by the other user communication devices in the group. This is particularly beneficial when communication resources from the network to the user communication devices (downlink) are relatively in abundance, while communication resources from the user communication devices towards the network (uplink) are somewhat constrained. This is typical of cellular communications systems, which use wireless technology between the user communication devices and the network.
Some cellular communication systems, also allow a user communication device to operate in either a receive-only mode or a receive-transmit mode, where a user communication device that is in the receive-only mode consumes less system resources. In such systems, operation in the receive-transmit mode requires the use of additional control channels and thus increases overhead. Typically, transition of a user communication device between modes of operation is not instantaneous; therefore, if a user communication device transitions to the receive-transmit mode even to send a small amount of traffic, the device may remain in that mode consuming a larger percentage of system resources for a longer period of time. Secondly, system resources may also be consumed for signaling associated with the transitions between modes. Finally, a user communication device may consume power at a higher rate while in the receive-transmit mode. Thus the cost associated with sending even a small amount of traffic in the uplink may be significant and should be avoided when possible.
While group communications may be inherently well suited for cellular communication systems that have an ability to send downlink traffic to multiple user communication devices simultaneously, there is need for a floor control system that minimizes uplink signaling. In particular, there is a need for floor control system that minimizes the likelihood that a user communication device will transition to receive-transmit mode to send a floor request signal that will be rejected by the controller device.